Therapeutic opportunities in targeting the protective arm of the renin-angiotensin system to improve insulin sensitivity: a mechanistic review.

In recent years, the knowledge of the physiological and pathophysiological roles of the renin-angiotensin system (RAS) in glucose metabolism has advanced significantly. It is now well-established that blockade of the angiotensin AT1 receptor (AT1R) improves insulin sensitivity. Activation of the AT2 receptor (AT2R) and the MAS receptor are significant contributors to this beneficial effect. Elevated availability of angiotensin (Ang) II) for interaction with the AT2R and increased Ang-(1-7) formation during AT1R blockade mediate these effects. The ongoing development of selective AT2R agonists, such as compound 21 and the novel Ang III peptidomimetics, has significantly advanced the exploration of the role of AT2R in metabolism and its potential as a therapeutic target. These agents show promise, particularly when RAS inhibition is contraindicated. Additionally, other RAS peptides, including Ang IV, des-Asp-Ang I, Ang-(1-9), and alamandine, hold therapeutic capability for addressing metabolic disturbances linked to type 2 diabetes. The possibility of AT2R heteromerization with either AT1R or MAS receptor offers an exciting area for future research, particularly concerning therapeutic strategies to improve glycemic control. This review focuses on therapeutic opportunities to improve insulin sensitivity, taking advantage of the protective arm of the RAS.

Game-changing breakthroughs to redefine the landscape of the renin-angiotensin-aldosterone system in health and disease.

Novel perspectives on the role of the renin-angiotensin-aldosterone system (RAAS) offer a groundbreaking understanding of the system's role in health and illness. Our understanding of the role of the RAAS in several diseases, such as heart failure, hypertension, metabolic disorders, and chronic renal disease, has been broadened by recent studies. Specific variations in RAAS pathways can affect the course of disease and response to treatment, as shown by genetic and molecular research. The dynamic and fast-evolving nature of RAAS research described in this special issue might transform our approach to managing renal, neurological, and cardiovascular health, among other disease conditions, including cancer.

Functional diversification within the heme-binding split-barrel family.

Due to neofunctionalization, a single fold can be identified in multiple proteins that have distinct molecular functions. Depending on the time that has passed since gene duplication and the number of mutations, the sequence similarity between functionally divergent proteins can be relatively high, eroding the value of sequence similarity as the sole tool for accurately annotating the function of uncharacterized homologs. Here, we combine bioinformatic approaches with targeted experimentation to reveal a large multi-functional family of putative enzymatic and non-enzymatic proteins involved in heme metabolism. This family (homolog of HugZ (HOZ)) is embedded in the "FMN-binding split barrel" superfamily and contains separate groups of proteins from prokaryotes, plants, and algae, which bind heme and either catalyze its degradation or function as non-enzymatic heme sensors. In prokaryotes these proteins are often involved in iron assimilation, whereas several plant and algal homologs are predicted to degrade heme in the plastid or regulate heme biosynthesis. In the plant Arabidopsis thaliana, which contains two HOZ subfamilies that can degrade heme in vitro (HOZ1 and HOZ2), disruption of AtHOZ1 (AT3G03890) or AtHOZ2A (AT1G51560) causes developmental delays, pointing to important biological roles in the plastid. In the tree Populus trichocarpa, a recent duplication event of a HOZ1 ancestor has resulted in localization of a paralog to the cytosol. Structural characterization of this cytosolic paralog and comparison to published homologous structures suggests conservation of heme-binding sites. This study unifies our understanding of the sequence-structure-function relationships within this multi-lineage family of heme-binding proteins and presents new molecular players in plant and bacterial heme metabolism.

Role of Local Angiotensin II Signaling in Bladder Function.

Local renin-angiotensin signaling is present within various organ systems of the body. Angiotensin II signaling acts as a crucial mechanism of the renin-angiotensin signaling system. In this manuscript, we review current literature regarding local angiotensin II signaling in the urinary bladder. Our interest in this pathway is due to its potential role in interstitial cystitis/bladder pain syndrome and other bladder diseases, which are chronic in nature and negatively affect patients' quality of life. Current treatments for bladder diseases are generally ineffective due to our lack of understanding of their pathophysiology. We evaluate literature investigating angiotensin II signaling in the bladder across several perspectives, including local expression and production, functional properties, tissue morphology, and clinical implications. Further, we identify gaps in knowledge and suggest areas where we can improve our understanding of angiotensin II signaling in the bladder.

Implications of ß-Arrestin biased signaling by angiotensin II type 1 receptor for cardiovascular drug discovery and therapeutics.

Angiotensin II receptors, Type 1 (AT1R) and Type 2 (AT2R) are 7TM receptors that play critical roles in both the physiological and pathophysiological regulation of the cardiovascular system. While AT1R blockers (ARBs) have proven beneficial in managing cardiac, vascular and renal maladies they cannot completely halt and reverse the progression of pathologies. Numerous experimental and animal studies have demonstrated that ß-arrestin biased AT1R-ligands (such as SII-AngII, S1I8, TRV023, and TRV027) offer cardiovascular benefits by blocking the G protein signaling while retaining the ß-arrestin signaling. However, these ligands failed to show improvement in heart-failure outcome over the placebo in a phase IIb clinical trial. One major limitation of current ß-arrestin biased AT1R-ligands is that they are peptides with short half-lives, limiting their long-term efficacy in patients. Additionally, ß-arrestin biased AT1R-ligand peptides, may inadvertently block AT2R, a promiscuous receptor, potentially negating its beneficial effects in post-myocardial infarction (MI) patients. Therefore, developing a small molecule ß-arrestin biased AT1R-ligand with a longer half-life and specificity to AT1R could be more effective in treating heart failure. This approach has the potential to revolutionize the treatment of cardiovascular diseases by offering more sustained and targeted therapeutic effects.

The Relationship among SARS-CoV-2, Vaccine Spike Protein, Renin- Angiotensin System, and Epilepsy.

Several comorbidities and illnesses have emerged after the COVID-19 pandemic and the introduction of vaccination based on a slightly modified SARS-CoV-2 spike protein. One of these diseases is epilepsy, where the dysfunctional RAS plays a crucial role in the propagation of the disorder. SARS-CoV-2 infects host cells by utilizing the angiotensin-converting enzyme Type 2 (ACE2) receptor, which allows the virus to infect various cell types, including those in the lungs, nasopharynx, kidneys, lymph nodes, small intestine, stomach, spleen, and brain, leading to widespread organ damage. Once SARS-CoV-2 binds to the ACE2 receptor, it can lead to the overactivation of the ACE/Ang II/AT1R axis. Consequently, higher levels of Ang II activate several deleterious pathways that promote inflammation, contributing to inflammatory responses in the body and exacerbating conditions such as seizures. Additionally, the excitatory effect of AT1R by Ang II excess due to ACE2 inhibition by SARS-CoV-2 or by the vaccine Spike protein may play a further role in the mechanism contributing to epilepsy.

Effect of angiotensin II type 1 receptor antibodies on graft function and survival in paediatric kidney transplant recipients.

HLA donor specific antibodies (DSA) are implicated in antibody-mediated rejection (AMR), graft dysfunction and failure in kidney transplant (KT) recipients. Non-HLA antibodies including angiotensin II type 1 receptor (AT1R) may also play a role in AMR, impact graft function and survival. Data is limited in paediatric KT cohorts. We aimed to assess the prevalence and effect of pre-transplant AT1R antibodies on rejection, graft function and survival in paediatric KT recipients. This was a retrospective cohort study conducted across two paediatric centres including KT recipients with a pre-transplant AT1R antibody level. Outcomes included rejection, de novo DSA formation, graft function, failure, proteinuria and hypertension. Of 71 individuals, 72% recorded a positive pre-transplant AT1R Ab level (≥17 U/mL). Over a median follow-up of 4.7 years, AT1R Ab positivity demonstrated a trend towards increased risk of rejection however was not statistically significant (HR 3.45, 95% CI 0.97-12.35, p-value 0.06). Sensitivity analysis with AT1R Ab levels of ≥25 U/mL (HR 2.05 95% CI 0.78-5.39, p-value 0.14) and ≥40 U/mL (HR 1.32, CI 95% 0.55-3.17, p-value 0.53) validated this. De novo DSA formation occurred more frequently with AT1R Ab positivity (41% vs. 20%, p-value 0.9). AT1R Ab was not associated with hypertension, proteinuria, graft failure or dysfunction. In conclusion, this cohort study demonstrated a high prevalence of pre-transplant AT1R Ab positivity (72%). AT1R Ab positivity demonstrated a trend towards increased risk of rejection and de novo DSA formation however did not meet statistical significance. There was no association between AT1R Ab and hypertension, proteinuria, graft failure or dysfunction.

BET degrader exhibits lower antiproliferative activity than its inhibitor via EGR1 recruiting septins to promote E2F1-3 transcription in triple-negative breast cancer.

The bromodomain and extraterminal domain (BET) family proteins serve as primary readers of acetylated lysine residues and play crucial roles in cell proliferation and differentiation. Dysregulation of BET proteins has been implicated in tumorigenesis, making them important therapeutic targets. BET-bromodomain (BD) inhibitors and BET-targeting degraders have been developed to inhibit BET proteins. In this study, we found that the BET inhibitor MS645 exhibited superior antiproliferative activity than BET degraders including ARV771, AT1, MZ1 and dBET1 in triple-negative breast cancer (TNBC) cells. Treatment with MS645 led to the dissociation of BETs, MED1 and RNA polymerase II from the E2F1-3 promoter, resulting in the suppression of E2F1-3 transcription and subsequent inhibition of cell growth in TNBC. In contrast, while ARV771 displaced BET proteins from chromatin, it did not significantly alter E2F1-3 expression. Mechanistically, ARV771 induced BRD4 depletion at protein level, which markedly increased EGR1 expression. This elevation of EGR1 subsequently recruited septin 2 and septin 9 to E2F1-3 promoters, enhancing E2F1-3 transcription and promoting cell proliferation rate in vitro and in vivo. Our findings provide valuable insights into differential mechanisms of BET inhibition and highlight potential of developing BET-targeting molecules as therapeutic strategies for TNBC.

Optimizing Image Quality with High-Resolution, Deep-Learning-Based Diffusion-Weighted Imaging in Breast Cancer Patients at 1.5 T.

The objective of this study was to evaluate a high-resolution deep-learning (DL)-based diffusion-weighted imaging (DWI) sequence for breast magnetic resonance imaging (MRI) in comparison to a standard DWI sequence (DWIStd) at 1.5 T. It is a prospective study of 38 breast cancer patients, who were scanned with DWIStd and DWIDL. Both DWI sequences were scored for image quality, sharpness, artifacts, contrast, noise, and diagnostic confidence with a Likert-scale from 1 (non-diagnostic) to 5 (excellent). The lesion diameter was evaluated on b 800 DWI, apparent diffusion coefficient (ADC), and the second subtraction (SUB) of the contrast-enhanced T1 VIBE. SNR was also calculated. Statistics included correlation analyses and paired t-tests. High-resolution DWIDL offered significantly superior image quality, sharpness, noise, contrast, and diagnostic confidence (each p < 0.02)). Artifacts were significantly higher in DWIDL by one reader (M = 4.62 vs. 4.36 Likert scale, p < 0.01) without affecting the diagnostic confidence. SNR was higher in DWIDL for b 50 and ADC maps (each p = 0.07). Acquisition time was reduced by 22% in DWIDL. The lesion diameters in DWI b 800DL and Std and ADCDL and Std were respectively 6% lower compared to the 2nd SUB. A DL-based diffusion sequence at 1.5 T in breast MRI offers a higher resolution and a faster acquisition, including only minimally more artefacts without affecting the diagnostic confidence.

Radiation Induced Skin Fibrosis (RISF): Opportunity for Angiotensin II-Dependent Intervention.

Medical procedures, such as radiation therapy, are a vital element in treating many cancers, significantly contributing to improved survival rates. However, a common long-term complication of such exposure is radiation-induced skin fibrosis (RISF), a complex condition that poses substantial physical and psychological challenges. Notably, about 50% of patients undergoing radiation therapy may achieve long-term remission, resulting in a significant number of survivors managing the aftereffects of their treatment. This article delves into the intricate relationship between RISF, reactive oxygen species (ROS), and angiotensin II (Ang II) signaling. It proposes the underlying mechanisms and examines potential treatments for mitigating skin fibrosis. The primary goal is to offer essential insights in order to better care for and improve the quality of life of cancer survivors who face the risk of developing RISF.

The Abbreviated Methacholine Challenge Test is Safe for Children.

OBJECTIVE: To evaluate the safety of an abbreviated methacholine challenge test (MCT) protocol in children. STUDY DESIGN: This prospective, observational study enrolled children aged 6 through 18 years referred for the MCT. The abbreviated protocol was initiated with a methacholine dose of 0.03 mg/ml and escalated in fourfold increments, unless the forced expiratory volume at 1 second decline exceeded 10%, at which point the next dose was only doubled. The safety of this abbreviated approach was assessed by monitoring adverse events, and specifically, decreases in forced expiratory volume at 1 second over 40%, hypoxemia, or uncontrollable cough. The number of methacholine doses and test duration were recorded and compared with estimated outcomes derived from the full-length MCT protocol. RESULTS: One hundred twelve participants, aged 13.7 years (±3.3), successfully completed the protocol. Fifty-seven (51%) presented a positive MCT response. No significant clinical adverse events were observed. Of all participants, 2.7% exhibited an exaggerated response, in line with previously reported findings for the full-length protocol. The abbreviated approach resulted in an estimated average time-savings of 18:19 minutes per participant, thus reducing test length by 22:47 minutes for a negative MCT and by 14:34 minutes for a positive outcome. CONCLUSIONS: This abbreviated MCT protocol is safe for children and effectively shortens the duration of the MCT.

Plasma exchange-sensitive syncytial glomerulopathy in a kidney transplant patient.

Microvascular inflammation (MVI), defined as the presence of glomerulitis and/or peritubular capillaritis, is the key histological lesion of anti-HLA donor-specific antibodies (DSA)-related antibody mediated rejection, but recently other possible mechanisms of MVI have emerged. However, except for peritubular capillary C4d deposition that is more frequently observed in the presence of anti-HLA-DSA, histological features are similar regardless of MVI origin. Therefore, accurately describing patterns of MVI may help differentiate etiologies and drive therapeutic choices. We describe the case of a kidney transplant recipient (primary nephropathy: autosomal dominant polycystic kidney disease) who underwent kidney biopsy for worsening renal function and new onset hypertension. Histologic findings showed severe microvascular inflammation with intense glomerulitis and presence of intracapillary multinucleated cells, positive on immunostaining for endothelial marker ETS-related gene (ERG). Focal intense peritubular capillaritis and early glomerular basement membrane reduplication, C4d negative, were observed, consistent with early chronic active ABMR. HLA-DSA were absent, but high level of anti-angiotensin II type-1 receptor (AT1R) antibodies (Ab) were detected (78 U/L, normal levels < 10 U/L). Two subsequent biopsies showed intense microvascular inflammation with diffuse peritubular capillaritis, and multinucleated, ERG-positive, endothelial cells were still seen in glomerular capillary loops. The patient was started on angiotensin receptor blockers (ARBs) and plasma exchange (PEX) sessions obtaining normalization of blood pressure and AT1R Ab and proteinuria reduction, but, after subsequent liver transplant, rituximab therapy failed to maintain remission and the patient remained PEX-dependent.

Effect of extracellular matrix stiffness on efficacy of Dapagliflozin for diabetic cardiomyopathy.

BACKGROUND: Extracellular matrix (ECM) stiffness is closely related to the progress of diabetic cardiomyopathy (DCM) and the response of treatment of DCM to anti-diabetic drugs. Dapagliflozin (Dapa) has been proven to have cardio-protective efficacy for diabetes and listed as the first-line drug to treat heart failure. But the regulatory relationship between ECM stiffness and treatment efficacy of Dapa remains elusive. MATERIALS AND METHODS: This work investigated the effect of ECM stiffness on DCM progression and Dapa efficacy using both in vivo DCM rat model and in vitro myocardial cell model with high glucose injury. First, through DCM rat models with various levels of myocardial injury and administration with Dapa treatment for four weeks, the levels of myocardial injury, myocardial oxidative stress, expressions of AT1R (a mechanical signal protein) and the stiffness of myocardial tissues were obtained. Then for mimicking the stiffness of myocardial tissues at early and late stages of DCM, we constructed cell models through culturing H9c2 myocardial cells on the polyacrylamide gels with two stiffness and exposed to a high glucose level and without/with Dapa intervention. The cell viability, reactive oxygen species (ROS) levels and expressions of mechanical signal sensitive proteins were obtained. RESULTS: The DCM progression is accompanied by the increased myocardial tissue stiffness, which can synergistically exacerbate myocardial cell injury with high glucose. Dapa can improve the ECM stiffness-induced DCM progression and its efficacy on DCM is more pronounced on the soft ECM, which is related to the regulation pathway of AT1R-FAK-NOX2. Besides, Dapa can inhibit the expression of the ECM-induced integrin ß1, but without significant impact on piezo 1. CONCLUSIONS: Our study found the regulation and effect of biomechanics in the DCM progression and on the Dapa efficacy on DCM, providing the new insights for the DCM treatment. Additionally, our work showed the better clinical prognosis of DCM under early Dapa intervention.

Optical perturbation of Agtr1a-containing neurons and afferents within the caudal nucleus of the solitary tract modulates sodium intake.

Angiotensin-II (Ang-II) production is driven by deviations in blood volume and osmolality, and serves the role of regulating blood pressure and fluid intake to maintain cardiovascular and hydromineral homeostasis. These actions are mediated by Ang-II acting on its type 1a receptor (AT1aR) within the central nervous system and periphery. Of relevance, AT1aR are expressed on sensory afferents responsible for conveying cardiovascular information to the nucleus of the solitary tract (NTS). We have previously determined that optical excitation of neurons and vagal afferents within the NTS that express AT1aR (referred to as NTSAT1aR) mimics the perception of increased vascular stretch and induces compensatory responses to restore blood pressure. Here, we test whether NTSAT1aR are also involved in the modulation of water and sodium intake. We directed the light-sensitive excitatory channelrhodopsin-2 (ChR2) or inhibitory halorhodopsin (Halo) to Agtr1a-containing neurons and measured water and sodium chloride (NaCl) intake in the presence and absence of optical stimulation within the NTS during various challenges to fluid homeostasis. Optical perturbation of NTSAT1aR modulates NaCl intake, such that excitation attenuates, whereas inhibition increases intake. This effect is only observed in the water-deprived condition, suggesting that NTSAT1aR are involved in the regulation of sodium intake during an imbalance in both the intracellular and extracellular fluid compartments. Furthermore, optical excitation of NTSAT1aR increases c-Fos expression within oxytocinergic neurons of the paraventricular nucleus of the hypothalamus (PVN), indicating that the regulation of sodium intake by NTSAT1aR may be mediated by oxytocin. Collectively, these results reveal that NTSAT1aR are sufficient and necessary to modulate sodium intake relative to perceived changes in vascular stretch.

Activation AMPK in Hypothalamic Paraventricular Nucleus Improves Renovascular Hypertension Through ERK1/2-NF-κB Pathway.

Hypertension is a globally prevalent disease, but the pathogenesis remains largely unclear. AMP-activated protein kinase (AMPK) is a nutrition-sensitive signal of cellular energy metabolism, which has a certain influence on the development of hypertension. Previously, we found a down-regulation of the phosphorylated (p-) form of AMPK, and the up-regulation of the angiotensin II type 1 receptor (AT1-R) and that of p-ERK1/2 in the hypothalamic paraventricular nucleus (PVN) of hypertensive rats. However, the exact mechanism underlying the relationship between AMPK and AT1-R in the PVN during hypertension remains unclear. Thus, we hypothesized that AMPK modulates AT1-R through the ERK1/2-NF-κB pathway in the PVN, thereby inhibiting sympathetic nerve activity and improving hypertension. To examine this hypothesis, we employed a renovascular hypertensive animal model developed via two-kidney, one-clip (2K1C) and sham-operated (SHAM). Artificial cerebrospinal fluid (aCSF), used as vehicle, or 5-amino-1-ß-D-ribofuranosyl-imidazole-4-carboxamide (AICAR, an AMPK activator, 60 µg/day) was microinjected bilaterally in the PVN of these rats for 4 weeks. In 2K1C rats, there an increase in systolic blood pressure (SBP) and circulating norepinephrine (NE). Also, the hypertensive rats had lowered expression of p-AMPK and p-AMPK/AMPK, elevated expression of p-ERK1/2, p-ERK1/2/ERK1/2 and AT1-R, increased NF-κB p65 activity in the PVN compared with the levels of these biomarkers in SHAM rats. Four weeks of bilateral PVN injection of AMPK activator AICAR, attenuated the NE level and SBP, increased the expression of p-AMPK and p-AMPK/AMPK, lessened the NF-κB p65 activity, decreased the expression of p-ERK1/2, p-ERK1/2/ERK1/2 and AT1-R in the PVN of 2K1C rats. Data from this study imply that the activation of AMPK within the PVN suppressed AT1-R expression through inhibiting the ERK1/2-NF-κB pathway, decreased the activity of the sympathetic nervous system, improved hypertension.

Tumor microenvironment (Part I): Tissue integrity in a rat model of peripheral neural cancer.

ICAM-1 (intercellular adhesion molecule 1) and MPZ (myelin protein zero) are thought to be a factor in the integrity of nerve tissues. In this report, we attempted to trace the expression of ICAM-1, responsible for cell-to-cell adhesion, and of MPZ, the main constituent of myelin sheath, in malignant tissues of the sciatic nerve (SN) in inbred male Copenhagen rats. AT-1 Cells (anaplastic tumor 1) were injected in the perineurial sheath, and tissues of the SNs were collected after 7, 14 and 21 days and compared to a sham-operated group of rats (n = 6 each). Tissues were sectioned and histologically examined, under light microscope, and stained for measuring the immunoreactivity of ICAM-1 and MPZ under laser scanning microscope. The cancer model was established, and the tumor growth was confirmed. ICAM-1 showed severe decreases, proportional to the growing anaplastic cells, as compared to the sham group. MPZ revealed, however, a distinct defensive pattern before substantially decreasing in a comparison with sham. These results support the notion that malignancies damage peripheral nerves and cause severe axonal injury and loss of neuronal integrity, and clearly define the role of ICAM-1 and MPZ in safeguarding the nerve tissues.

Direct GPCR-EGFR interaction enables synergistic membrane-to-nucleus information transfer.

We addressed the heteromerization of the epidermal growth factor receptor (EGFR) with G-protein coupled receptors (GPCR) on the basis of angiotensin-II-receptor-subtype-1(AT1R)-EGFR interaction as proof-of-concept and show its functional relevance during synergistic nuclear information transfer, beyond ligand-dependent EGFR transactivation. Following in silico modelling, we generated EGFR-interaction deficient AT1R-mutants and compared them to AT1R-wildtype. Receptor interaction was assessed by co-immunoprecipitation (CoIP), Förster resonance energy transfer (FRET) and fluorescence-lifetime imaging microscopy (FLIM). Changes in cell morphology, ERK1/2-phosphorylation (ppERK1/2), serum response factor (SRF)-activation and cFOS protein expression were determined by digital high content microscopy at the single cell level. FRET, FLIM and CoIP confirmed the physical interaction of AT1R-wildtype with EGFR that was strongly reduced for the AT1R-mutants. Responsiveness of cells transfected with AT1R-WT or -mutants to angiotensin II or EGF was similar regarding changes in cell circularity, ppERK1/2 (direct and by ligand-dependent EGFR-transactivation), cFOS-expression and SRF-activity. By contrast, the EGFR-AT1R-synergism regarding these parameters was completely absent for in the interaction-deficient AT1R mutants. The results show that AT1R-EGFR heteromerisation enables AT1R-EGFR-synergism on downstream gene expression regulation, modulating the intensity and the temporal pattern of nuclear AT1R/EGFR-information transfer. Furthermore, remote EGFR transactivation, via ligand release or cytosolic tyrosine kinases, is not sufficient for the complete synergistic control of gene expression.

Modulator Effect of AT1 Receptor Knockdown on THP-1 Macrophage Proinflammatory Activity.

Currently, it is known that angiotensin II (AngII) induces inflammation, and an AT1R blockade has anti-inflammatory effects. The use of an AT1 receptor antagonist promotes the inhibition of the secretion of multiple proinflammatory cytokines in macrophages, as well as a decrease in the concentration of reactive oxygen species. The aim of this study was to determine the effect of AT1 receptor gene silencing on the modulation of cytokines (e.g., IL-1ß, TNF-α, and IL-10) in THP-1 macrophages and the relation to the gene expression of NF-κB. MATERIALS AND METHODS: We evaluated the gene expression of PPAR-γ in THP-1 macrophages using PMA (60 ng/mL). For the silencing, cells were incubated with the siRNA for 72 h and telmisartan (10 µM) was added to the medium for 24 h. After that, cells were incubated during 1 and 24 h, respectively, with Ang II (1 µM). The gene expression levels of AT1R, NF-κB, and cytokines (IL-1ß, TNF-α, and IL-10) were measured by RT-qPCR. RESULTS: We observed that silencing of the AT1 receptor causes a decrease in the expression of mRNA of proinflammatory cytokines (IL-1ß and TNF-α), NF-κB, and PPAR-γ. CONCLUSIONS: We conclude that AT1R gene silencing is an alternative to modulating the production of proinflammatory cytokines such as TNF-α and IL-1ß via NF-κB in macrophages and having high blood pressure decrease.

Ang II-induced contraction is impaired in the aortas of renovascular hypertensive animal model.

Abstract: Renin-angiotensin system plays a critical role in blood pressure control, and the abnormal activation of the AT1 receptor contributes to the development of renovascular hypertension. This study aimed to evaluate the underlying cellular signaling for AT1 receptor activation by Ang II and to compare this mechanism between aortas from 2K-1C and 2K rats. Effects of antagonists and inhibitors were investigated on Ang II-induced contractions in denuded or intact-endothelium aortas. The AT1 receptor antagonist abolished Ang II-induced contraction in 2K-1C and 2K rat aortas, while AT2 and Mas receptors antagonists had no effect. Endothelial nitric oxide synthase inhibition increased the maximal effect (Emax) of Ang II in 2K, which was not changed in 2K-1C aortas. It was associated with lower eNOS mRNA levels in 2K-1C. Endothelium removal increased the Emax of Ang II in 2K-1C and mainly in 2K rat aortas. Nox and COX inhibition did not alter Ang II-induced contraction in 2K and 2K-1C rat aortas. However, AT1 expression was higher in 2K-1C compared to 2K rat aortic rings, whereas expression of phosphorylated (active) IP3 receptors was lower in 2K-1C than in 2K rats. These results demonstrate that endothelium removal impairs Ang II-stimulated contraction in the aorta of 2K-1C rats, which is associated with the reduction of IP3 receptor phosphorylation and activation. In addition, eNOS plays a critical role in Ang II-induced contraction in 2K rat aortas. It is possible that the high Ang II plasma levels could desensitize AT1 receptor in 2K-1C rats, leading to impaired IP3 receptors activation.

ACE2 mediates tryptophan alleviation on diarrhea by repairing intestine barrier involved mTOR pathway.

The membrane-delimited receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), angiotensin-converting enzyme 2 (ACE2), which is expressed in the intestine, collaborates with broad neutral amino acid transporter 1 (B0AT1). Tryptophan (Trp) is transported into intestinal epithelial cells by ACE2 and B0AT1. However, whether ACE2 and its binding protein B0AT1 are involved in Trp-mediated alleviation of intestinal injury is largely unknown. Here, we used weaned piglets and IPEC-J2 cells as models and found that ACE2/B0AT1 alleviated lipopolysaccharide (LPS)-induced diarrhea and promoted intestinal barrier recovery via transport of Trp. The levels of the aryl hydrocarbon receptor (AhR) and mechanistic target of rapamycin (mTOR) pathways were altered by ACE2. Dietary Trp supplementation in LPS-treated weaned piglets revealed that Trp alleviated diarrhea by promoting ACE2/B0AT1 expression, and examination of intestinal morphology revealed that the damage to the intestinal barrier was repaired. Our study demonstrated that ACE2 accompanied by B0AT1 mediated the alleviation of diarrhea by Trp through intestinal barrier repair via the mTOR pathway.